Pulse generator



1951 J. A. KRUMHANSL ETAl 2,536,316

PULSE GENERATOR Filed May 29. 1946 REFERENCE PULSE GENERATOR T0. UTILIZATION MAIN PULSE. GENERATOR I I T INVENTOR.

: "Am i JAMES A. KRUMHANSL GENERATOR I J 7 FIG. 3

ATTORNEY Patented Jan. 2, 1951 UNITED STATES PATENT OFFICE PULSE GENERATOR.

Application May 29, 1946', Serial No. 673,005

- Claims; (Cl'. 250-46) This invention relates to pulse generators; and

more. particularly to pulse selector circuits for causing an operation to take place in response toselecton of certain pulses.

It is an object of our invention to provide a new and improved pulse generator including a delay circuit which results in the generation of a pulse at a predetermined time. The characteristic features of our circuit enable its opera.-

of short duration are coupled to the grid of the electron-discharge device from a low impedance source so that the charge on the blocking oscillator grid capacitor quickly retturns to its nor.- mal charge after cessation ofeachv pulse. At other predetermined intervals, pulses of lower A capacitor is connected in series repetition rate are applied to the grid of the 0s cillator through a unilateral device. mentioned pulses charge the capacitor to such a value that the next succeeding pulse from the first source will render conducting the discharge These last device and a pulse will appear intheoutput wlnding of the transformer;

Our invention will be better understood when the following detailed description is read in connection with the accompanying drawings in,

which Fig. 1 is a circuit diagram of one, embodiment of our invention, Fig. 2 is a diagram useful in explaining the operation of the circuit of Fig.

1, Fig. 3 is a second embodiment of our invention, and Fig. 4 is a diagram helpful to, an understanding of the circuit shown in Fig. 3.

Referring to Fig. I, there is illustrated a transformer-coupled blocking or s'ngle-swing oscillatorincluding an electron discharge device I having an anode or plate 2, a control-electrode. =or grid 3', and a cathode 4-. The transformer 5- has an output winding 6, and a plate or anode winding I connected between anode 2 and a suitable source of positive potential winding 8 of transformer 5 is connected between ground and illustrative form of my invention shown in Fig. 1, the source H, which may also be referred to as the main pulse generator, may consist of a singleswing or blocking oscillator comprising discharge device I? and three-Winding transformer 43', a capacitor [4 being connected in series with the grid l5 of the discharge device l2, shown as a triode, and one winding of transformer I3. As is widely understood, periodically recurring pulses appear in the output winding [6 of transformer 13, the time between pulses being determined primarily by the value of the gr'd resistance l1 and the capacitor M, which determine the time constant of the circuit. It may be well to note that. the value of capacitor M is in part fixed by pulse. width requirements.

The pulses from source H are coupled to the control-electrode 3 in some sutable manner, as by means of a suitable capacitor [8.

Capacitors 9 and I8 and winding 8 of transformer 5 form a potential divider, the source of potential being output winding it of transformer is. The amplitude of the pulses from source II and the values of capactors 9 and I8 are chosen so that the potential at control-electrode 3 is normally below cut-off. This normal condition is illustrated in Fig. 2 which represents the potenti'al at grid or electrode 3 and wherein the pulses l9 represent the main pulses appled to control electrode 3 from source I! and cut-off is represented by the dashed line. The transformer winding It should have a low impedance so that the charge on capacitor 53 closely follows the applied pulses.

In order to cause discharge device I to become conducting at predetermined times, there is: provided a source 20 of reference pulses which, in the form of our invention shown in Fig. 1,

' comprises a blocking oscillator like that serving as the main pulse generator or source II. The reference pulse generator at is designed to produce output pulses of lower repet'tion rate than that; of the. pulses from source H by suitable one side. of a capacitor 9; the other terminal of capacitor 9 being connected to the control electrode 3.

nesting the cathode t to a suitable source of The discharge device is biased below cut-off. Suitable bias may be obta ned by conchoiceof circuit constants. Preferably, the reference pulses occur at rates which are sub-multipl'es of the main pulses. If desired, synchronizing means comprising a unilateral device such as the d ode 34, may be provided to render more positive. potential, as through apotentiometer l0,

for example.

There. is provided a source H of periodically recurring pulses of short. duration. in the erence pulses.

The reference pulses are applied to the control electrode 3 through a suitable coupling device 22 and a potential dropping res'stor 28.

the; torm ofour invention shown in Fig. l,

the device 22 is a triode having an anode 23 connected to a suitable source of positive potential, a cathode 24 connected to control electrode 3 through the resistor 28, and a control electrode 25 connected to capacitor 2|. A resistor 26 connected between grid or control electrode 25 and ground furnishes a discharge path for capacitor 2|.

Since discharge device 22 conducts only in one direction, there is no discharge path for capacitor 9 for charges imparted thereto by pulses from generator or source 20. Hence the charge on capacitor 9 remains substantially constant as indicated in Fig. 2 wherein the numeral 21 represents a reference pulse and the dotted line represents the capac tor charge due to the reference pulse. Hence, the potential at control electrode 3 is maintained substantially constant at the level of the reference pulses until the receipt of another pulse.

Pulses 21 have an initial peak, as shown in Fig. 2, indicating that capacitor 9 is not charged to the maximum potential of the reference pu ses. Charg ng of inter-electrode and other inherent capacitances accounts for some discrepancy in this regard and unavoidable leaka e paths exist which cause the potential at electrode 3 to tend to follow the decay of the reference pulses.

The amplitude of the reference pulses is chosen such that the addition of the next main pulse increases the grid potential in the positive direct on sufficiently to render conducting the dischar e device I to discharge the capacitor 9 and prepare the circuit for another cvcle. Conduction throu h device I causes formation of an output pulse in transformer winding 6.

Insertion of the resistor 28 in the cathode lead of device 22 serves to integrate and limit the peak at the initiation of each reference pulse 21. The value of res stor 28 wi l be such that peaks of the reference p ls s will not trigger dischar e device I and a variable resistance may be used if control of the amplitude of the peaks is desired.

Referr ng to Fi 2, the c rcuit described may be considered to be a dividin system in wh ch division is by the factor three, since the reference pulses occur at the rate of one for each three main pulses. By adjusting circuit constants of either or both sources of pulses. division by other denominators may be obtained. On the other hand, the c rcuit mav be described as a delayby-one circuit, since the first main p lse fo lowing a reference pulse triggers the discharge device I. A delay-by-two or other number may be obtained by adiusting the pulse rates of the sources I I and 2!! so that reference pulses will be supp ied at a sufiiciently greater rate than the main pulses.

Reference has been made to the use of a unilateral device in the path of application of reference pulses to the dischar e dev ce I. A triode 22 is shown in Fig. 1. However, inasmuch as the function of device 22 is to impress reference pulses on the capacitor 9 and control electrode 3 and to prevent any substantial discharge of the capacitor 9 during the decay of the pulses and thereafter, any other suitable device which will pass pulses in only one direct on may be employed, such as a suitable crystal. In Fig. 3 a modified circuit including a diode 29 as a unilateral device is shown.

The circuit of Fig. 3 is also provided with synchronizing means to render more certain the relative times of occurrence of pulses from the sources of main and reference pulses. The electron discharge device 30 of reference pulse generator 39 comprises an anode 3|, connected to a suitable source of positive potential through the plate winding of transformer 38, a grounded cathode 32 and a control electrode 33. Pulses from source II are applied not only to control electrode 3 of device I, but also to control electrode 33 of device 30 through a unilatera device, such as a diode 34. and a resistance 35. The

prov sion of diode 34 will ca se capacitor 36 to count pulses and a ter a pred termined number has been received, the control electrode potential reaches cut-off and device 30 becomes conductive to initiate eneration of a pulse. Hence. the time of discharge of device 3!] coinc des with the time of a main pul e (each main pulse or fo lowing receipt of a p edet rm n d number of p lses depending upon the time constant of the circuit), and the overshoot which accom an es the decay of pulses produced occ rs a short time thereafter. Fi 4 illustrates the time sequence of puls produ tion. Bv revers n the sense of the outp t winding 3'! of, trans o mer 38. the o ershoots ma h used as re erence p ses. in which case the d schar e device I alwa s becomes conduct ve at the same int rval after receipt of a referencepu se to enerate an o tp t pulse in windin 6 of trans ormer the delay being equal to the time la of the overshoots.

' What we claim is:

1. In o ina i n with. a ulse e erator having an electron rli nhar e devi e in l d a contro ele trode. sa d di ch r e device bein biased to be norma ly non-conductive. m ans f r rend ring said d s harge de ice cond ctive at predet rm ned times comprisin a unilateral device having first and second terminals: a source of reference pulses coupled to said first terminal; a connection including a resistance element between said terminal and said control electrode; a source of main pulses having a repetition rate which is an integral multiple of that of said reference pulses, said main pulse source being coupled to said control electrode and the combined amplitudes of said reference pulses and said main pulses being sufficient to render said discharge device conductive; and means for maintaining said reference pulse source in phase with the output of said main pulse source.

2. In combination with a pulse generator having an electron discharge device including a control electrode, said discharge device being biased to be normally non-conductive, means for rendering said discharge device conductive at predetermined times comprising: a unilateral device having first and second terminals; a source of reference pulses coupled to said first terminal; a connection including a resistance element between said second terminal and said control electrode; a source of main pulses having a repetition rate which is an integral multiple of that of said reference pulses, said main pulse source being coupled to said control grid and the combined amplitudes of said reference pulses and said main pulses being sufficient to render said discharge device conductive; and means including a twoelectrode electron discharge device for maintaining said reference pulse source in phase with the output of said main pulse source.

3. In combination with a pulse generator having a first electron discharge device including a, first control electrode, said first discharge device being biased to be normally non-conductive, means for rendering said first discharge device conductive at predetermined times comprising: a

second electron discharge device having a second control electrode, a cathode, and an anode; a source of reference pulses coupled to said second control electrode; a connection including a resistance element between said cathode and said first control electrode; means for applying a positive potential to said anode; a source of main pulses having a repetition rate which is an integral multiple of that of said reference pulses, said main pulse source being coupled to said first control electrode and the combined amplitudes of said reference pulses and said'main pulses being surficient to render said first discharge device conductive; and means for maintaining said refer-- enee pulse source in phase with the output of said main pulse source.

4. In combination with a pulse generator having a first electron discharge device including a control grid, said first discharge device being biased to be normally non-conductive, means for rendering said first discharge device conductive at random times comprising: a second electron discharge device having a cathode and an anode; a source of reference pulses coupled to said anode; a connection including a resistance element between said cathode and said control grid; and a source of main pulses of greater repetition rate than said reference pulses, said main pulse source being coupled to said control grid and the combined amplitudes of said reference pulses and. said main pulses being sufficient to render said first discharge device conductive.

5. In combination with a pulse generator having a first electron discharge device including a control grid, said first discharge device being biased to be normally non-conductive, means for rendering said first discharge device conductive at predetermined times comprising: a second electron discharge device having a cathode and an anode; a source of reference pulses coupled to said anode; a connection including a resistance element between'said cathode and said control grid; a source of main pulses having a repetition rate which is an integral multiple of that of said reference pulses, said main pulse source being coupled to said control grid and the combined amplitudes of said reference pulses and said main pulses being sufficient to render said first discharge device conductive; and means for maintaining said reference pulse source in phase with the output of said main pulse source.

JAMES A. KRUMHANSL. GLENN H. MILLER.

REFERENCES CITED The following references are of record in the 'file of this patent:

UNITED STATES PATENTS Number Name Date 1,979,484 Mathes Nov. 6, 1934 2,113,011 White Apr. 5, 1938 2,171,536 Bingley Sept. 5, 1939 FOREIGN PATENTS Number Country Date 510,881 Great Britain Aug. 8, 1939 

